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COVID-19 vaccine study supports flexible gap between doses

A standard two-dose Pfizer-BioNTech or Oxford-AstraZeneca vaccine showed a greater antibody increase when given at a 12-week interval compared to a four-week interval, an NIHR-supported study found.

Only Pfizer-BioNTech followed by Oxford-AstraZeneca recorded a significantly stronger immune response in the 12-week versus four-week interval groups and only at 28 days following a second dose. This persisted to six months following the second dose.

They are the latest findings from the University of Oxford-led Com-COV study, which has published a paper in the Lancet Respiratory Medicine and recruited at eight sites including Oxford Vaccine Group at the Churchill Hospital, Oxford.

The study supports flexibility in first and second doses across all vaccine schedules studied, which can be helpful in countries where vaccine supply may be inconsistent. No safety concerns were raised in the study of 730 participants.

Matthew Snape, Professor in Paediatrics and Vaccinology at the University of Oxford, and Chief Investigator on the trial, said: “This paper summarises data that have been made available to policy makers globally during the pandemic, providing vital information the impact of using short vs long intervals for a range of COVID-19 vaccine schedules.

These data are relevant not only to COVID-19 vaccines, but also how future vaccines using mRNA and viral vectored platforms against different diseases may be best deployed.”

Professor Andrew Ustianowski, NIHR Clinical Lead for COVID-19 Vaccination Programme and Joint National Infection Specialty Lead, said: “We continue to learn more about how we can get the very best out of the vaccine doses we have available globally. These latest findings from the Com-COV study show how we can get the most out of current vaccine supplies - something which is key when it comes to vaccinating those in Low-Middle Income Countries.

"It's thanks to the continued efforts of research staff and participants across the country which help to provide us with such important data, which shapes COVID-19 vaccine policy across the world.

“As always we are indebted to the fantastic participants that took part in this study, and to the NIHR and Vaccine Taskforce for providing the funding and infrastructure support that made this possible.”

It is the first trial reporting randomised data looking at the effect of time interval and prophylactic paracetamol use for standard and mixed vaccine schedules using the Oxford-AstraZeneca and Pfizer-BioNTech vaccines.

The Com-COV study first reported robust immune responses following mixed Oxford/Pfizer schedules in June 2021, and data from the study also informed the UK’s 2021 winter booster programme.